Re: [RFA]: simulator build failures with parallel make

["H . J . Lu" <hjl@lucon.org>]

On Sun, Apr 15, 2001 at 01:47:27PM -0700, J.T. Conklin wrote:
> >>>>> "HJ" == H J Lu <hjl@lucon.org> writes:
> >>>>> "Andrew" == Andrew Cagney <ac131313@cygnus.com> writes:
> Andrew> With that dependency added without -j does the generator get
> Andrew> run twice?  I've this memory of a strange querk with make
> Andrew> dependencies and files being created as a sideeffect.
> >> 
> >> No.  
> >> 
> >> But now that you've mentioned it, I recall that rules with multiple
> >> targets will be executed once per target with -j (at least with GNU
> >> make).  This can be worked around by creating a psuedo-target to 
> 
> HJ> Please don't add any workaround.  Just provide complete
> HJ> dependencies, [...]
> 
> And just what workaround do you think I'm adding? 
> 
> HJ> [...] any make, including GNU make, will be happy.
> 
> Untrue.  GNU make will invoke the commands for a rule with multiple
> targets multiple times when used with -j.  Bug or feature, this must
> be accomidated.
> 
> For example:
> 
>         $ cat Makefile
>         all: foo.tab.c foo.tab.h
> 
>         foo.tab.c foo.tab.h: foo.y
>                 $(YACC) -b foo -p foo -d $?
> 
>         $ gmake -j
>         yacc -b foo -p foo -d foo.y
>         yacc -b foo -p foo -d foo.y
> 
> In many cases, this must be guarded against.  A rule with two targets
> occured only once in the four simulator makefiles I touched. And that
> one already handled it by introducing a pseudo-target to serialize 
> the make.  For the above makefile, the equivalent would be:
> 
>         $ cat Makefile
>         all: foo.tab.c foo.tab.h
> 
>         foo.tab.c foo.tab.h: foo-stamp
> 
>         foo-stamp: foo.y
>                 $(YACC) -b foo -p foo -d $?
>                 touch $@
> 
> So what exactly is your complaint about my patch.
> 

That is a bug in Makefile and that is why we have ylwrap. See how it is
done in ld/Makefile.*, binutils/Makefile.* and gas/Makefile.*. Do

# grep YLWRAP */Makefile.in

in binutils tree. I can anaswer any questions if those Makefile.in
files are not clear enough.


H.J.